British JournaI of Obstetrics and Gynaecology October 1976. Vol83. pp 768-770

THE RESPONSE OF THE FETAL HEART RATE TO AMNIOCENTESIS M. RON AND

W . Z . POLISHUK Department of Obstetrics and Gynaecology, Hadassdh University Hospital Jerusalem, Israel Summary Fetal heart rate monitoring during I07 amniocenteses suggested that acceleration of the fetal heart rate indicated fetal well-being. Eight out of the 19 fetuses who did not show this response (as against 2 out of the 88 others) had a low Apgar score at birth.

per minute which was sustained for at least two minutes.

PAPERSdealing with the hazards and complications of amniocentesis (Grove et a/, 1973; Ron et JI, 1971) stress the importance of fetal heart rate monitoring after the procedure. This paper deals with the changes in fetal heart rate observed during and after amniocentesis and fetal outconie.

RFSULTS In 88 amniocenteses (82.2 per cent) the fetal heart rate showed acceleration which started within 30 seconds of puncture of the amniotic sac. The acceleration ranged between 20 to 60 beats per minute and the tachycardia lasted between 2 to 30 minutes. In all 10 patients in whom there was a five minute interval between puncture of the abdominal and uterine walls, acceleration of the fetal heart rate occurred after penetration of the uterine wall. Of the 88 patients in Rhom the fetal heart rate showed the acceleration response, 86 (97-7 per cent) delivered healthy babies uith a good Apgar score. Only in two patients (2.3 per cent) was there evidence of fetal distress before or during labour (Table 11). In 19 amniocenteses (17.8 per cent) there was no fetal heart rate acceleration response; 8 patients (42.2 per cent) were delivered of infants with a low Apgar score and there were two perinatal deaths (Table TI). The other 1 1 patients (57.8 per cent) were delivered of a healthy baby with a good Apgar score. Two short illustrative case reports are given.

METHODS Using a Hewlett Packard cardiotocograph (No. 8020A), the fetal heart rate mas recorded in I07 amniocenteses done between the 32nd to the 42nd week of gestation. Amniocentesis was performed in cases of rhesus isoimmunization and in patients in whom induction of labour or examination of amniotic fluid was indicated for the various conditions listed in Table 1. After locating the placenta with radioisotopes or the Doptone, amniocentesis was done with a No. 18 or 19 needle which was usually introduced in the midline below the umbilicus. The recording of the fetal heart rate was started 10 minutes before amniocentesis and was continued for up to 90 minutes afterwards. In 10 patients a five minute interval was allowed between the puncture of the abdominal and the uterine walls. ‘Fetal heart rate acceleration’ was defined as an increase of at least 20 beats 768

FETAL HEART RATE AND AMNIOCENTESIS

TABLEI Indicationsfor amniocentesis

Indication Rhesus isoimniunization Placental insufficiency Pre-eclampsia Diabetes Postmaturity Loss of fetal movements (Ron et a/, 1976) Other conditions (bad obstetric history, hydramnios, uterine scar, etc.) Total

Number

Per cent

13 4 4 12 59

11.6 3.5 3.5 10.5 52.7

6

4.8

14

12.5

-

112

Patietit I . M.S., 30 years old, had an amniocentesis in the 42nd week of her normal fourth pregnancy. The amniotic fluid was clear and the bubble test was positive in dilution of 1 : 5. N o acceleration pattern was seen. A repeat amniocentesis three days later yielded meconium stained amniotic fluid. A Caesarean section was performed and a baby with an Apgar score of 3 was delivered, with no apparent cause for the distress apart from postmaturity. Patient 2. B.C., 32 years old, had an amniocentesis in the 36th week of her third pregnancy

769

because of rhesus incompatibility. The amniotic fluid was yellow. There was no fetal heart rate acceleration pattern. Fetography suggested a diagnosis of hydrops fetalis. The patient was induced and delivered of a hydropic baby with an Apgar score of 3; the child died after two hours.

DISCUSSION The responses of the fetal heart rate to drugs such as pethidine (Huch et ul, 1974), diazepam (Scher et d, 1972) and local anaesthetics (Vasicka et al, 1971; ZiIianti et ul. 1970) have been studied and the responses to atropine (Ionascu. 1971; .lunge and Loch, 1971; Zacutti and Brugnali, 1971), isoxsuprine (Boyd et a/, 1974) and oxytocin (Boyd et ul, 1974; Cooper et a], 1975) have been suggested as tests of feto-maternal transport and fetal reserve. The response of fetal heart rate to maternal exercise was suggested by Ponierance et nl (1974) as a test for placental insufficiency. Fetal heart rate acceleration in response to sound and vibration was described by Griniwade et a1 (1971) and by Sakabe et al (1973). Others have used external light to stimulate the fetus (Polishuk et al, 1975). Lee r t al(1975) suggested that fetal activity acceleration may serve as a

TABLEI1 Details about infants with low Apgar score at one minute

Maturity No' Name (weeks)

Tndication for amniocentesis

Fluid

Fetal heart rate response

Interval between amniocentesis and delivery (hours)

Birth wzight kg

Mode of delivery

I

2.1.

42

Post maturity

clear

acceleration

12

2

K.A. S.L. B.M. A.G. B.C. H.S.

42 42 41 31 36 36

Post maturity Post maturity Uncertain maturity Diabetes mellitus Erythroblastosis Placental insufficiency

clear clear clear clear yellow clear

acceleration

24 24 120 12 12 6

9

B.L. M.S.

38 42

Fetal tachycardia Postmaturity

clear meconium

96 48

Vaginal (vacuum extraction) Vaginal 3.10 3.25 Vaginal Vaginal 3.00 3.70 Vaginal 2.20* Vaginal 2.00 Elective CS 3.20 Vaginal 4.00 Elective

10

M.H.

36

Gestational diabetes meconium

24

3.80

3 4 5 6

I 8

* Hydropic infant which died two hours after delivery

3.60

cs

Vaginal

Apgar score at one minute 3 5 5

4 4 3 3 2 3 5

770

RON AND POLISHUK

method of anteparturn evaluation of fetal well-being. From our observations it seems that fetal heart rate acceleration is the normal response of the fetus to amniocentesis. The absence of this response may indicate that the fetus is in relatively poor condition. The nature of the stimulus to the fetus during amniocentesis is not clear. It could be that the entry into the amniotic cavity of the needle causes fluid waves, unnoticed uterine contraction, a direct tactile stimulus, or a combination of these mechanisms. Of the 107 cases studied. there were 88 who showed fetal heart rate acceleration and only 2 of these fetuses had a Iow Apgar score at birth. Of the 19 cases without acceleration, 8 fetuses had a low Apgar score and the difference is statistically significant (P< 0.1). We do not suggest amniocentesis for the sole purpose of recording fetal heart rate response but feel that monitoring of the fetal heart rate during well-indicated amniocentesis could produce % aluable information about fetal wellbeing. REFERENCES Boyd, I. E., Chamberlain, G. V. P., and Fergussen, I. L. C. (I 974): Journal of Obstetrics and Gynaecology of the British Commonwealth, 81, 120. Cooper, J. M., Saffronoff, E. C., and Bolegnese, R. J. (1975): Obstetrics and Gynecology, 45, 27.

Grimwade, J. C., Walker, D. W., Bartlett, M., Gordon, S., and Wood, C. (1971): American Journal of Obstetrics and Gynecology, 109, 86. Grove, C., Trobetta, G. C., and Amstey, M. S. (1973): American Journal of Obsietrics and Gynecology, 115, 1154. Huch, A., Huch, R., Lindmark, G., and Rooth, G. (1974): Journal of Obstetrics and Gynaecology of the British Commonwealth, 81, 608. Ionascu, D. R. (1971): Gyntcologie et obstktrique, 70,465. Junge, H. D., and Loch, W. (1971): Zeifschrifr fiir Geburtshilje und Gynakologie, 174, 22. Lee, C. Y., Diloreto, P. C., and O’Lane, J. M. (1975): Ubsretrics and Gynecology, 45, 142. Polishuk, Z. W., Lauffer, N., and Sadovsky, E. (1975): Harefuah, 9, 395. Pomerance, J. J., Cluck, L., and Lynch, V. A. (1974): Obstetrics and Gynecology, 44, 383. Ron, M., Anteby, S., Diamant, Y . Z., and Polishuk, 2. W. (1974): International Journal of Gynaecology and Obstetrics, 12, 172. Ron, M., Yaffe, H., and Sadovsky, E. (1976): Obstetrics and Gynecology (in press). Sakabe, N., Ooki, T., and Itani, E. (1973): Audiology Japonica, 16, 147. Scher, J., Hailey, D. M., and Beard, R. W. (1972): Journal of Obstetrics and Gynaecology of the British Commonwealth, 79, 635. Vasicka, A., Robertazzi, R., and Raji, M. (1971): Obstetrics and Gynecology, 38, 500. Zacutti, A., and Brugnali, C. A. (1971): Minerva Ginecologica, 23, 779. Zilianti, M., Salazal, J. R., Aller, J. V., and Aguero, 0. (1970): Obstetrics and Gynecology, 36, 881.

The response of the fetal heart rate of amniocentesis.

British JournaI of Obstetrics and Gynaecology October 1976. Vol83. pp 768-770 THE RESPONSE OF THE FETAL HEART RATE TO AMNIOCENTESIS M. RON AND W . Z...
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